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SOURCES OF VARIABILITY IN COLLECTION AND PREPARATION OF PAINT AND LEAD-COATING SAMPLES
Citation:
Harper, S L. AND W. F. Gutknecht. SOURCES OF VARIABILITY IN COLLECTION AND PREPARATION OF PAINT AND LEAD-COATING SAMPLES. JOURNAL OF ENVIRONMENTAL MONITORING 3(3):335-340, (2001).
Description:
Chronic exposure of children to lead can result in permanent physiologic impairment. Since surfaces coated with lead-containing paints and varnishes are potential sources of exposure, it is extremely important that reliable methods for sampling and analysis be available. The sources of variability in the collection and preparation of samples were investigated to improve the performance and comparability of methods and to ensure that data generated will be adequate for its intended use. Paint samples of varying sizes (areas and masses) were collected at different locations across a variety of surfaces including metal, plaster, concrete, and wood. Homogenization and subsampling steps were found to be the principal sources of variability related to the size of the sample collected. A variety of grinding techniques were compared. Manual mortar and pestle grinding for at least 1.5 minutes and mechanized grinding techniques were found to generate similar homogenous particle size distributions required for aliquots as small as100 mg. When 342 samples were evaluated for sample weight loss during mortar and pestle grinding, 4% had 20% or greater loss with a high of 41%. Analysis of samples from different locations on apparently identical surfaces were found to vary by more than a factor of 2 both in lead (Pb) concentration (mg cm-2 or %) and areal coating density (g cm-2). Analyses of substrates were performed to determine Pb remaining after coating removal. Levels as high as 1% Pb were found in some substrate samples, corresponding to more than 35 mg cm-2 Pb. In conclusion, these sources of variability must be considered in development and/or application of any sampling and analysis methodologies.
This research was funded by the U.S. Environmental Protection Agency under contracts 68-D1-0009 and 68-D5-0040. This work has been reviewed in accordance with the U.S. Environmental Protection Agency's peer and administrative review process and approved for presentation and publication. Mention of trade names or commercial products does not constitute endorsement or recommendation for use.